The innate immune response is critical to the survival of plants and animals. The response is mediated by the detection of pathogen-associated molecular patterns (PAMPs) (also referred to as microbe-associated molecular patterns) or avirulence (Avr) proteins by pathogen recognition receptors (PRRs; also called pattern recognition receptors or disease resistance proteins). In animals, a family of cytosolic PRRs that contain a nucleotide-binding oligomerization domain (NOD) mediates the apoptotic and inflammatory responses critical to protection from pathogen invasion. Plants also contain a set of intracellular PRR proteins, called NB-LRR (nucleotide binding-leucine rich repeat) R proteins, which are structurally similar to animal NOD proteins. These plant NB-LRR proteins are characterized by a tripartite domain architecture consisting of an N-terminal coiled-coil (CC) or Toll/interleukin-1 receptor (TIR) domain, a central NB domain, and a C-terminal LRR domain (Hammond-Kosack and Jones (1997) Annu. Rev. Plant Physiol. Plant Mol. Biol. 48: 575-607) and typically recognize pathogen-derived Avr proteins (also called effectors) (Van der Biezen and Jones (1998) Trends Biochem. Sci. 23: 454-456).
Rice blast is one of the most devastating diseases of rice and occurs in all areas of the world where rice is cultivated. More than 70 blast R genes that confer resistance to geographically different sets of the rice blast pathogen Magnaporthe oryzae isolates have been identified to date (Ballini et al. (2008) Mol. Plant. Microbe Interact. 21: 859-868). For example, Pib confers robust resistance to a majority of the Japanese Magnaporthe oryzae isolates (Wang et al. (1999) Plant J. 19: 55-64). In contrast, Pi37 confers only partial resistance to Japanese isolates but complete resistance to Chinese isolates of the same pathogen. Hence, the isolation of multiple R genes is required to fully understand the molecular basis of the resistance to rice blast. Such characterization of these genes will facilitate development of agronomically useful rice cultivars through markerassisted breeding or through transgenic approaches.
To date, a total of nine rice blast resistance genes have been cloned and characterized: Pib, Pita, Pi9, Pi2 and Piz-t, Pi-d2, Pi36, Pi37, and Pikm. With the exception of Pi-d2, a non-RD receptor-like kinase, these genes all encode NB-LRR type proteins. Distinct features of these cloned rice blast resistance genes have been observed. The Pib protein contains a duplicated NB region. Pita lacks a classic LRR but contains a leucine-rich domain (LRD) consisting of imperfect repeats of various lengths. A single amino acid difference at the Pita LRD was found to distinguish resistant from susceptible alleles. The allelic genes Pi2 and Piz-t show 8 amino acid differences within three consecutive LRRs, and these residues are responsible for resistance specificity. The Pi9 gene strongly resembles the Pi2 and Piz-t genes and is located within the same region on chromosome 6. The Pikm-mediated resistance requires two adjacent NB-LRR genes Pikm1-TS and Pikm2-TS. Among these cloned R genes, only Pita has been observed to interact with the corresponding Magnaporthe oryzae avirulence protein, AvrPita. Thus, defense signaling mediated by NB-LRR type proteins remains poorly characterized in rice.
It has been reported that Pi5 confers resistance to many Magnaporthe oryzae isolates collected from Korea and the Philippines (Wang et al. (1994) Genetics 136: 1421-1434). To gain a further understanding of the molecular basis of Pi5-mediated rice blast resistance, we used a map-based method to isolate the Pi5 genomic region. We previously mapped Pi5 to a 170-kb interval on the short arm of chromosome 9 in the RIL260 rice cultivar (Jeon et al. (2003) Molecular Genetics and Genomics 269: 280-289).
According to Korean Patent Registration No. 10-0764563, a gene for inducing resistance to a plant disease, a vector comprising the gene and a transformant obtained from the vector are described. Furthermore, according to Korean Patent Registration No. 10-0701302, plant disease-resistant ogpr 1 gene separated from wild rice, the amino acid sequence of the gene, and a transformant using the same are described. However, said gene is different from the gene of the present invention.